DESCRIPTION (Adapted from applicants' abstract) The applicants propose that airway epithelial cells provide critical biochemical signals for regulating immunity and inflammation. In support of this possibility, they have found that epithelial cells express a functional set of immune-response genes (ICAM-1, IRF-1, TAP1, and RANTES) under the control of an interferon-gamma (IFN-,gamma) signal transduction pathway. For example, epithelial cell expression of intercellular adhesion molecule-1 (ICAM- 1) mediates leukocyte trafficking (adhesion, transmigration, and retention) in the airway epithelium by serving as a receptor for leukocyte B2-integrins. In that context, they have obtained evidence that ICAM-1 mediates epithelial-immune cell interactions that may allow for "appropriate" immune responses (e.g., to a respiratory virus infection) or "inappropriate" responses (e.g., airway inflammation in asthma ). This application is based on the observation that ICAM-1 expression on airway epithelial cells depends on a specific IFN-gamma-driven signal transduction pathway that relies in turn on the binding of the activated transcription factor Statl to the ICAM-1 gene promoter region. In addition to this DNA/protein interaction, Statl also appears to interact with the transcriptional coactivator p3OO and the transcription factor Sp1 to fully activate gene transcription. The aim of this application is to determine the structural features of Statl that allow for interaction with p3OO and Sp1 and the role of these interactions in activating transcription for ICAM-1 and related immune-response genes. This information may then be used to modify ICAM-1 gene activation and the airway inflammatory response through blockade of enhancer-pathways and potentiation of repressor-pathways (e.g., Statl dominant-negative mutation and adenoviral EIA protein expression). Accordingly, The specific aims are to: I. Define the structural basis and functional role of Statl/p3OO interaction in ICAM-1 gene activation. They will use their primary culture human airway epithelial cell model to define the interaction between Statl and the transcriptional coactivator p3OO. Structure-function studies of Statl and p3OO will be accomplished in experiments that define protein/protein interactions and gene transcription for wild-type and mutated forms of Statl and p3OO. II. Define the structural basis and functional role of Statl/Spl-interaction in ICAM-1 gene activation. They will take advantage of the same cell model to characterize the structural domains required for the transcriptional synergy between Statl and Spl. Structure-function studies of Stat1 and Sp1 will be accomplished using protein/protein, protein/DNA, and gene transcription experiments for wild-type and mutated forms of Statl and Spl. (End of Abstract)